Tiahleigh Palmer's foster brother fronts court

The foster brother of slain Brisbane schoolgirl Tiahleigh Palmer has told a court he is "acutely remorseful" for obstructing an investigation into her death.

Josh Thorburn, 21, was supported by his grandmother when he appeared in Beenleigh District Court for sentencing on Tuesday.

He and his mother Julene have pleaded guilty to perjury and attempting to pervert the course of justice after providing false testimony to the Crime and Corruption Commission during a secret hearing in 2016.

Thorburn’s lawyer said in court he is deeply sorry for his role in the alleged cover-up.

Tiahleigh's body was found on the banks of the Pimpana River in 2015. ()The Thorburn family have all been charged with varying roles in the alleged murder of Tiahleigh Palmer. ()

"He recognises he obstructed an extremely difficult and challenging investigation. He is acutely remorseful and sorry."

Tiahleigh's body was found on the banks of the Pipama Pimpana River in 2015, sparking an 11-month investigation into the Thorburn family's alleged involvement.

Thorburn's father Rick has been charged with Tiahleigh's murder, while his younger brother Trent faces incest charges.